Idiopathic Thrombocytopenic Purpura
An autoimmune bleeding disorder where the immune system destroys its own blood platelets, causing easy bruising and bleeding.
Emergency Management: Life-threatening hemorrhage requires immediate IVIG 1 g/kg, IV Methylprednisolone 1g, AND platelet transfusions (even though they will be rapidly consumed, they provide transient hemostasis). May add Romiplostim or recombinant Factor VIIa.
Immune Thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by a low platelet count (thrombocytopenia, <100,000/microL) leading to a bleeding tendency, without an identifiable underlying cause.
Detailed Overview
ITP results from pathogenic autoantibodies (usually IgG) targeting platelet surface glycoproteins (such as GPIIb/IIIa). These antibody-coated platelets are rapidly destroyed by macrophages in the spleen. Furthermore, these antibodies can inhibit megakaryocyte platelet production in the bone marrow. It presents acutely in children (often post-viral) and chronically in adults.
Epidemiology & Demographics
Incidence is 2-4 per 100,000 adults per year, and slightly higher in children. In adults, it is more common in females (2:1 ratio) mostly between ages 20-50. In children, it occurs equally between sexes, peaking at ages 2-5.
Etiological Mechanism
Idiopathic (Primary ITP) due to loss of self-tolerance. Secondary ITP can be triggered by HIV, Hepatitis C, H. pylori, SLE, or lymphoproliferative disorders like CLL.
Primary Causes
Autoimmune destruction (Primary ITP)
Viral infections (EBV, CMV, HIV, Hep C)
Helicobacter pylori infection
Autoimmune conditions (Systemic Lupus Erythematosus)
IgG autoantibodies bind to platelet glycoproteins (GPIIb/IIIa, GPIb/IX). The Fc portions of these bound antibodies are recognized by Fc-gamma receptors on tissue macrophages, predominantly in the spleen, leading to phagocytosis and premature platelet clearance. Additionally, T-cell mediated cytotoxicity attacks megakaryocytes in the bone marrow, impairing compensatory platelet production. Bleeding risk increases significantly when platelet count falls below 20,000-30,000/microL.
Diagnostic Criteria & Guidelines
A diagnosis of exclusion. Isolated thrombocytopenia (platelets < 100,000/microL) with otherwise normal CBC and peripheral smear (absence of schistocytes, blasts). No clinically apparent associated conditions.
For platelets < 30,000/microL or clinical bleeding: 1. Corticosteroids: Dexamethasone 40 mg PO daily for 4 days OR Prednisone 1 mg/kg PO daily for 1-2 weeks then tapered. 2. IVIG: 1 g/kg IV for 1-2 days if a rapid increase in platelets is needed (e.g., active bleeding or prior to surgery).
Second-Line & Adjunctive Therapy
Thrombopoietin receptor agonists (TPO-RAs) like Eltrombopag 50 mg PO daily or Romiplostim 1 mcg/kg subQ weekly. Rituximab 375 mg/m2 IV weekly for 4 weeks. Fostamatinib (Syk inhibitor).
Surgical & Procedural Management
Laparoscopic splenectomy is considered for chronic, refractory ITP in patients who fail or cannot tolerate medical therapy, providing a long-term curative response in about 60-70% of patients.
Patient Counseling & Advice
Warn patients to seek immediate emergency care for worst-headache-of-life, visual changes, or neurological symptoms, as these may herald intracranial hemorrhage. Review safe activity guidelines.
Follow-Up & Monitoring Schedule
Weekly CBC until platelet count stabilizes > 50,000/microL, then monthly or as needed. Monitor for signs of infection if on long-term steroids or post-splenectomy.
Preventive Strategies
No primary prevention. Secondary prevention of bleeding relies on maintaining platelets safely above 20,000-30,000/microL.
In children, 80% have spontaneous resolution within 6 months. In adults, the disease is usually chronic, but long-term survival is nearly normal with modern treatments.